Propeller and method of making the same



L. T. FREDERICK.

PROPELLER AND METHOD OF MAKING THE SAME.

APPLICATION FILEDADECJU, 1918.

1,367, 1 31. Patented Feb. 1, 1921.

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WITNESFSES: INVENTOR ffJTza/mm/ Low: 1' Freder/kk W BY 7 ATTbRNEY UNIT STATES PATENT OFFICE.

LOUIS T. FREDERICK, OF WILKINSBURG. PENNSYLVANIA, ASSIGNOB TOWESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- PBOIELLER AND METHOD OF MAKING THE SAME.

Specification of Letters Patent.

Patented Feb. 1, 1921.

Application filed December 30, 1918. Serial No.268,955.

To all whom it may concern:

desirable features of a -Be it known that I, LOUIS T. FREDERICK, a citizen of the United States, and a resident of Wilkinsbur in the county of Allegheny and State of ennsylvania, have invented a new and useful Improvement in Propellers and Methods of Making the Same, of which the following is a specification.

- My invention relates to air screws or ropellers and more particularly to prope lers ofthe type comprising superimposed layers of fibrous sheet material impregnated with a hardened binder.

Heretofore, propellers of this character have been made in which duck, or similar woven sheet material, has been employed and they have been successful in operation. Also, propellers of this character have been made of paper and satisfactorily operated. It has been found, however, that a propeller formed of paper is cheaper than one formed of duck, possesses greater mechanical strength and is also more rigid. This latter feature is particularly desirable, as there is less tendency for the pitch of the propeller to change under operating conditlons and thereby change the load upon the engine so that it will run at different speeds under different operating conditions.

It has further been found that paper propellers have a slightly greater tendency to split under unusual strains, being somewhat more brittle than duck propellers, and also that they are apt to crack somewhat at the surface because of fatigue of the paper.

In view of these facts, the primary object of my present invention resides in constructing a propeller which will combine both the paper propeller and those of a duck propeller.

With these and otherobjects in view, my invention will be more fully described, illustrated in the drawin in the several views of which COIIGSPOIMfi IIg numerals indicate like parts, and then particularly pointed out in the claims.

Figure 1 is a plan view of the thrust face of a propeller constructed in accordance with my invention; Fig. 2 is a series of transverse sections taken through one of the blades on substantially the lines indicated in Fig. 1; Figs. 3 and 4 are plan views of certain of the layers employed in constructing the propeller, and Fig. 5 is a plan view of a covering layer employed in the propeller construction.

Broadly speaking, my invention resides in the provision of a propeller body comprismg superimposed layers of paper impregmated with a hardened phenolic condensation product and in providing this body with a covering of one or more layers of duck, or, in some, instances, cotton batting, impregnated with a hardened phenolic condensation product, the body and its covering being compacted and hardened into a unitaII'y propeller by-the same curing operation.

n practising my invention, I ma form the propeller body by the method dlsclosed in detail in a copending application filed by me Dec. 30, 1918, Serial there pointed out, a body is formed by superlmposlng a plurality of layers of sheet material, impregnated with a suitable binder, and cut to the proper sizes and shapes, so that, their blade-forming portlons are reversely twisted, a substantially propeller-shaped body is provided in which the hub-forming portions of the layers are disposed substantially 1 parallel to the hub faces while the bladeorming portions are disposed substantially parallel to the thrust faces of the blades.

Covers of duck, impregnated with a phenolic condensation product and cut to the proper sizes and shapes to fit smoothly over the thrust and back faces of the propeller, may then be applied to the body thus assembled and the body, together with its covers, may be disposed in a mold of suitable character and compacted and rendered solid by the application of heat and pressure which will harden the binder.

In the drawings, I have disclosed a propeller 1, embodying my invention, which comprises a propeller body formed of superimposed layers 2 of paper, impregnated with a phenolic condensation product, certain of these layers bein shown in Figs. 3 and 4. Inclosing this body is a cover formed of front, or thrust, and back layers 3 and 4, respectively, of duck impregnated with the same binder. The shape of the front covering layer is sufficiently indicated in Fig. 1, showing the front or thrust face of the propeller, while the shape of the back covering No. 268,954. As

layer 4 is fully shown in Fig, 5, which is a 75 when they are stacked and plan view of such layer. These layers are so proportioned and shaped as to fully inclose the paper body of the propeller when the latter has been compressed in a mold.

By the foregoing means, I provide a propeller having the cheapness, rigidity and mechanical strength of a paper propeller combined with the strength at the hub against splitting and the non-fatiguing surface of a duck propeller.

Although I have disclosed but a single method of arranging the various layers of sheet material to form the body of the propeller, it will be obvious that other methods may be employed. For lnstance, the body may be formed by the method disclosed in a copending application filed by D. A. Dickey, Dec. 30, 1918, Serial No. 268,949 and assi ned to the Westinghouse Electric &

anufacturing Company, in which the layers are disposed to lie throughout their entire length parallel with the faces of the hub. No limitations, therefore, are to be imposed upon my invention other than those indicated in the appended claims.

I claim as my invention:

1. A propeller comprising a body of superimposed layers of fibrous material impregnated with a hardened binder and a covering of fibrous material impregnated with a hardened binder.

2. A propeller comprising a body of superimposed layers of paper impregnated with a hardened binder and a covering of woven material impregnated with the same binder.

3. A propeller comprising a body of superimposed layers of paper and a covering of woven material, both the body and covering being impregnated with a hardened phenolic condensation product as a. blnder.

4. A propeller comprising a coverlng of Woven material impregated with a binder and an inclosed body of fibrous material impregnated with a hardened binder, the material of the body having greater rigidity than that of the covering.

5. A propeller comprising a body formed of superimposed layers of fibrous sheet material impregnated with a hardened binder in which the hub-forming portions of the layer are disposed parallel to the faces of the hub while the remaining portions are twisted to lie substantially parallel with the thrust faces of the blades, and sheets of fibrous material impregnated with a hard- 1ejnrczld binder forming a covering for the 6. The method of forming a propeller which comprises forming a body of superimposed layers of fibrous sheet material impregnated with a binder, placing covering layers of fibrous sheet material also impregnated with a binder over the body and compressing the entire body with its covering while curing the binder. v

7. The method of forming a propeller which comprises superimposing a plurality of layers of paper impregnated with a phenolic condensation product as a binder, to form a propeller-shaped body in which the hub-forming portions of the layers are disposed substantially parallel to the faces of the hub and the blade-forming portions are disposed substantially parallel to the thrust faces of the blades, disposing layers of woven sheet material, impregnated with a phenolic condensation product, against the thrust and back faces of the propeller body thus assembled, and subjecting the entire body with its covering to heat and pressure, in a mold, to compact the body and harden the binder.

In testimony whereof I have hereunto subscribed my name this 21st day of Dec, 1918.

LOUIS T. FREDERICK. 

